Add find rectangle

Author: igorwojda

README.md

@@ -77,10 +77,12 @@ time. Take your time before you take a look at the presented solution. **Good lu
 - [Fizz Buzz](src/test/kotlin/com/igorwojda/integer/fizzbuzz/desc.md)
 - [Caesar Cipher](src/test/kotlin/com/igorwojda/string/caesarcipher/desc.md)
 - [Has repeated char](src/test/kotlin/com/igorwojda/string/hasrepeatedcharacter/desc.md)
+- [Has repeated char](src/test/kotlin/com/igorwojda/string/hasrepeatedcharacter/desc.md)
 
 **Warrior** 
 
 - [Spiral matrix generator](src/test/kotlin/com/igorwojda/matrix/spiralmatrixgenerator/desc.md)
+- [Find rectangle](src/test/kotlin/com/igorwojda/matrix/findrectangle/desc.md)
 - [Queue](src/test/kotlin/com/igorwojda/queue/basic/desc.md)
 - [Combine queues](src/test/kotlin/com/igorwojda/queue/combine/desc.md)
 - [Stack](src/test/kotlin/com/igorwojda/stack/basic/desc.md)

misc/PuzzleGroups.md

@@ -127,7 +127,6 @@ We use sliding window instead of nested loops which decreases complexity from `O
 - [Print numbers with steps](../src/test/kotlin/com/igorwojda/integer/printnumber/steps/desc.md)
 - [Pyramid generator](../src/test/kotlin/com/igorwojda/integer/pyramidgenerator/desc.md)
 - [Reverse Int](../src/test/kotlin/com/igorwojda/integer/reverse/desc.md)
-- [Spiral matrix generator](../src/test/kotlin/com/igorwojda/integer/spiralmatrixgenerator/desc.md)
 - [Steps generator](../src/test/kotlin/com/igorwojda/integer/stepsgenerator/desc.md)
 
 ## String
@@ -149,6 +148,11 @@ We use sliding window instead of nested loops which decreases complexity from `O
 - [Find the vowels](../src/test/kotlin/com/igorwojda/string/vowels/desc.md)
 - [Format train route](../src/test/kotlin/com/igorwojda/list/formattrainroute/desc.md)
 
+## Matrix
+
+- [Spiral matrix generator](../src/test/kotlin/com/igorwojda/integer/spiralmatrixgenerator/desc.md)
+- [Find rectangle](src/test/kotlin/com/igorwojda/matrix/findrectangle/desc.md)
+
 ## Range
 
 - [Contains range?](../src/test/kotlin/com/igorwojda/range/containsrange/desc.md)

misc/template/puzzle/challange.kt misc/template/puzzle/challenge.kt

@@ -0,0 +1,84 @@
+package com.igorwojda.matrix.findrectangle
+
+import org.amshove.kluent.shouldBeEqualTo
+import org.junit.jupiter.api.Test
+
+private fun findRectangle(image: List<List<Int>>): List<Int?> {
+    TODO("not implemented")
+}
+
+private class Test {
+    @Test
+    fun `find rectangle in image 1`() {
+        val image = listOf(
+            listOf(1, 1, 1, 1, 1, 1, 1),
+            listOf(1, 1, 1, 1, 1, 1, 1),
+            listOf(1, 1, 1, 0, 0, 0, 1),
+            listOf(1, 1, 1, 0, 0, 0, 1),
+            listOf(1, 1, 1, 1, 1, 1, 1)
+        )
+
+        findRectangle(image) shouldBeEqualTo listOf(2, 3, 3, 5)
+    }
+
+    @Test
+    fun `find rectangle in image 2`() {
+        val image = listOf(
+            listOf(1, 1, 1, 1, 1, 1, 1),
+            listOf(1, 1, 1, 1, 1, 1, 1),
+            listOf(1, 1, 1, 1, 1, 1, 1),
+            listOf(1, 1, 1, 1, 1, 1, 1),
+            listOf(1, 1, 1, 1, 1, 1, 0)
+        )
+
+        findRectangle(image) shouldBeEqualTo listOf(4, 6, 4, 6)
+    }
+
+    @Test
+    fun `find rectangle in image 3`() {
+        val image = listOf(
+            listOf(1, 1, 1, 1, 1, 1, 1),
+            listOf(1, 1, 1, 1, 1, 1, 1),
+            listOf(1, 1, 1, 1, 1, 1, 1),
+            listOf(1, 1, 1, 1, 1, 0, 0),
+            listOf(1, 1, 1, 1, 1, 0, 0)
+        )
+
+        findRectangle(image) shouldBeEqualTo listOf(3, 5, 4, 6)
+    }
+
+    @Test
+    fun `find rectangle in image 4`() {
+        val image = listOf(
+            listOf(0, 1, 1, 1, 1, 1, 1),
+            listOf(1, 1, 1, 1, 1, 1, 1),
+            listOf(1, 1, 1, 1, 1, 1, 1),
+            listOf(1, 1, 1, 1, 1, 1, 1),
+            listOf(1, 1, 1, 1, 1, 1, 1)
+        )
+
+        findRectangle(image) shouldBeEqualTo listOf(0, 0, 0, 0)
+    }
+
+    @Test
+    fun `find rectangle in image 5`() {
+        val image = listOf(
+            listOf(1, 1, 1, 1, 1, 1, 1),
+            listOf(1, 1, 1, 1, 1, 1, 1),
+            listOf(0, 0, 1, 1, 1, 1, 1),
+            listOf(0, 0, 1, 1, 1, 1, 1),
+            listOf(1, 1, 1, 1, 1, 1, 1)
+        )
+
+        findRectangle(image) shouldBeEqualTo listOf(2, 0, 3, 1)
+    }
+
+    @Test
+    fun `find rectangle in image 6`() {
+        val image = listOf(
+            listOf(0)
+        )
+
+        findRectangle(image) shouldBeEqualTo listOf(0, 0, 0, 0)
+    }
+}

src/test/kotlin/com/igorwojda/matrix/findimage/challange.kt

@@ -0,0 +1,27 @@
+# Find rectangle
+
+## Instructions
+
+Image is represent as a simple 2D array where every pixel is a 1 or a 0. The image you get is known to have a single
+rectangle of 0s on a background of 1s.
+
+Write a function that takes in the image and returns list containing coordinates of top-left and bottom-right pixels
+represented as list of internees:
+
+[challenge.kt](challenge.kt) | [solution](solution.kt)
+
+## Examples
+
+Example 1
+
+```kotlin
+val image = listOf(
+    listOf(1, 1, 0, 0, 0, 1),
+    listOf(1, 1, 0, 0, 0, 1),
+    listOf(1, 1, 1, 1, 1, 1),
+    listOf(1, 1, 1, 1, 1, 1)
+)
+
+findRectangle(image)  // [0, 2, 1, 4]
+
+```

src/test/kotlin/com/igorwojda/matrix/findimage/desc.md

@@ -0,0 +1,30 @@
+package com.igorwojda.matrix.findrectangle
+
+// Time complexity: O(n*m)
+private object Solution1 {
+    private fun findRectangle(image: List<List<Int>>): List<Int?> {
+        var top: Pair<Int, Int>? = null
+        var bottom: Pair<Int, Int>? = null
+
+        image.forEachIndexed { rowIndex, rowItem ->
+            rowItem.forEachIndexed { columnIndex, pixelValue ->
+                if (pixelValue == 0) {
+                    if (top == null) {
+                        top = rowIndex to columnIndex
+                    } else {
+                        bottom = rowIndex to columnIndex
+                    }
+                }
+            }
+        }
+
+        // handle edge case where rectangle has 1 pixel
+        if (bottom == null) {
+            bottom = top
+        }
+
+        return listOf(top?.first, top?.second, bottom?.first, bottom?.second)
+    }
+}
+
+private object KtLintWillNotComplain